The present invention relates to a case for accommodating a magnetic tape cassette, and more particularly to a case for accommodating a magnetic tape cassette suitable for storing a magnetic tape cassette of a type intended for audio use.
A magnetic tape cassette per se has a front opening into which a magnetic head or the like is inserted when the cassette is loaded in a magnetic recording and reproducing apparatus, the cassette being arranged such that a magnetic tape wound around a pair of reel hubs travels across the front opening portions.
Due to this construction, dust or the like is liable to enter the cassette through the front opening portions. Also, there is the possibility of tape slackening or the like occurring in the magnetic tape wound on the hubs due to the rotation of same. Accordingly, for the purposes of preventing the cassette from occurring these problems and protecting the cassette per se, the cassette is often stored in an appropriate case, as will be described below.
FIGS. 10 and 11 show the basic structure of a conventional case. Specifically, the case 31 has a cover 32 having a pocket 34 for receiving a cassette 20, as well as a casing portion 36 having a pair of a cross-shaped stopper 37 adapted to enter a pair of shaft insertion holes 22 of the cassette 20. A pivot 38 respectively provided projectingly on left and right inner side walls of the casing portion 35 are rotatably fitted with holes provided in left and right side walls of the pocket 34 so that the casing portion 35 can be closed with the cover 32 like a door.
In a case where the aforementioned cassette 20 is accommodated in the case 31, the thick portion 21 of the cassette 20 is inserted into the pocket 34, and the cover 32 and the casing portion 35 are then closed. At this time, when the stoppers 37 enter the shaft insertion holes 22, an elongated member 37a of each stopper 37 engages any one of six spokes 23, as shown in FIG. 11.
Since the aforementioned spokes 23 are formed integrally with a pair of hubs 24 around which the magnetic tape is wound, large amounts of rotation of the hubs 24 can be prevented by retaining the spokes 23 by means of the elongated member 37a.
However, the width W.sub.1 of a wall portion of the elongated member 37a for retaining the spokes 23 is much smaller than the gap W.sub.0 between each spokes 23, so that a gap 2W.sub.2 which is determined by W.sub.0 -W.sub.1 is created. For this reason, there are cases where the magnetic tape can unwind to an undesirable degree due to a shaking movement permitted by the gap W.sub.2, despite the fact that the spoke 23 is retained by the elongated member 37a. Hence, there have been cases where tape slackening occurs in the tape located in the front opening portion of the cassette.
It should also be noted that if the width W.sub.1 of the wall portion of the elongated member is enlarged, although the amount of shaking movement of the hub 24 becomes smaller, there arises another drawback in that it becomes difficult for the stopper 37 to enter gap W.sub.0 between each spokes 23. In general, the less the harmful engagement of the spokes 23 with the elongated member 37a, the easier it is to close the case 31. For such reasons, the above shaking movement of the hub 24 in the unwinding direction of the tape is unavoidable to a certain extent.
Accordingly, it may occur that the tape in the magnetic tape cassette 20 accommodated in the case 32 is slackened to some degree. If the amount of tape slackening increases, the magnetic tape may be stuck on the surface of the tape guide during recording or reproduction. This can cause damage to the tape and, in an extreme case, result in tape jamming, thereby making tape movement impossible. To prevent this from happening, often the user will correct the tape slackening by rotating the aforementioned hub manually with his fingers as stick-shaped member before the magnetic tape is loaded in the recording and reproducing apparatus.